It's not just middle-aged people, TV, movies, fashion, entertainment, advertising, literature and all forms of expression that exist that seem inordinately obsessed with people in their twenties. It turns out that everyone is obsessed with people in their twenties, including you. New research on memory shows that we recall more stuff that happened during this time in our lives than any other. Which means that even when you're not in your twenties, you'll still be the most obsessed with yourself when you were. No one can escape it! It's like we're all Millennials forever!

A little-known but robust line of research shows that there really is something deeply, weirdly meaningful about this period. It plays an outsize role in how we structure our expectations, stories, and memories. The basic finding is this: We remember more events from late adolescence and early adulthood than from any other stage of our lives. This phenomenon is called the reminiscence bump.

Ah, the reminiscence bump. What a drug. The twenties aren't just when you're most likely to experiment with a bump of cocaine at a raging party — it's literally the cocaine bump of your entire life. So it shouldn't surprise you that researchers have been chasing this "reminiscence bump" since at least the 1980s, when chasing bumps was de rigeuer. Ok, that's the end of my drug-related jokes. But seriously, they aren't sure why this particular period is so loaded (OK, couldn't stop) with meaning, only that "autobiographical memories aren't distributed equally across the lifespan."

Instead, people tend to experience a period of childhood amnesia between birth and age 5, a reminiscence bump between age 10 and age 30 (with a particular concentration of memories in the early 20s), and at any age, a vivid period of recency from the present waning back to the end of the reminiscence bump.

There are some theories, of course. One is that, armed with a newly acquired mental firepower, young adults at this age are able to store memories with more high-end biological equipment, i.e., a killer working brain that can't wait to record that outrageous kegger or unexpected hookup. As that brain gets older and more doddering, it slows down and remembers less — or perhaps it has less exciting stuff to remember, like crossword puzzles and satisfying knitting. So is your brain kind of a fascist, or did you just get really boring later in life?

Or, could it be that because the twenties are front-loaded with novelty, the brain is more excited to jot that down? One 1988 study cited said 93 percent of our most vivid memories are first-timers, you know, your first kiss, first mumblecore movie (ha!), first exposure to the beat poets. Could the typical occurrence of all those twentysomething "firsts" like real jobs, leaving home, first children, first marriages be the culprit? Said memory-book author Joshua Foer:

The effect "does seem related to how adulthood is structured," he allowed. One's 20s form "the period that's the most varied and exciting; that's when you're hitchhiking across the country, going on lots of dates, having interesting encounters and learning about things for the first time."

"You're going to remember your trip hiking across Peru," Foer continued, "more than the year you spent sitting in your office doing the same job you'd been doing for the past five years."

Unless that office job was super exciting! But not so fast, says the piece. Studies like this always have other studies contradicting them. Turns out, it's just a small portion of memories in the bump that account for novel experiences.

...a 2010 study by Annette Bohn and Dorthe Berntsen created a form of reminiscence bump in schoolchildren without asking them to remember a thing. They asked a large group of students, aged 10 to 14, to write their life stories. Most of the future events the kids dreamed up clustered around young adulthood. If the reminiscence bump were merely an offshoot of how our brains store memories, the researchers argued, the children wouldn't have also privileged their 20s when projecting ahead.

But I have to ask — these are children who've seen television and magazines, which means they've been exposed to how our culture fetishizes the twenties. It's not like they dreamed up this stuff in a vacuum. Or, as all former children know, the twenties are the decade of first exposure to autonomy, so it makes perfect sense that children would regard with greater importance the first period of their lives in which they can eat as many cookies as they want and stay up all night, no questions asked.

But then there is the alternate theory: the "narrative perspective," which argues that our big memories are part of our attempt to make sense of who we are. In other words, we write a "life script" consisting of big moments that lays down the structure of our time on earth. These big moments, called "slots" are typically happy, and typically occur in the early years — late teens and early twenties. This study, it's worth noting, is contradicted by yet another one involving older Bangladeshi men and women who had more than one reminiscence bump, one in the late teens/early twenties period, and another between 35 and 55. Unlike the first bump, which contained the usual happy memoires, their second bump was a total bummer: sad wartime memories of the Bangladesh Liberation War.

Which leads us to another theory: We just remember the stuff that shapes our concept of who we are, good or bad, happy or sad, so long as it fits the bill of our self-directed life story. If it's a formative experience, it could be pulled from any period in life.

To test this theory, a team of scientists from England's University of Leeds devised a clever experiment. Noting that developmental psychologists have isolated the second and third decades as times of identity formation, they gathered a group of volunteers and tried to map the emergence of their self-perceptions. Participants were asked to complete 20 "I am" statements (e.g., "I am quick-tempered"; "I am a mother"). Then they were instructed to pick three statements and come up with 10 memories that seemed relevant to each. Finally, the volunteers were told to pinpoint as best they could the ages at which their three personality traits surfaced. If it's true that we remember more assiduously during bursts of self-making-and that these self-making periods tend to span our late teens and early 20s-a few things should happen, the researchers reasoned. First, participants should frequently date the unfurling of their "I am" statements to young adulthood. Second, the memories they summoned to support each "I am" statement should constellate around the age at which they believed the "I am" statement started to apply.

That was exactly what transpired. A majority of the memories associated with a particular self-image came from the very same year that the self-image developed. It seemed clear that the more salient a past experience was to your identity, the more luminous it grew in your memory. And what turned out to be the median age at which all these traits and self-concepts were acquired? 22.9.

This confirms the whole "the twenties are when you become who you are" thinking, or at least when you really figure out how you like to wear your hair. This is supported further by the discovery that lots of movie adaptations and remakes come about 20 years after the first one. The moment twentysomethings have a say in things and become creators in the culture, it's nostalgia time.

But since these studies don't go back earlier than the 1980s, isn't it possible there's an argument that we culturally condition ourselves to prize this period in our memory? It's no coincidence that in this culture at least, we value youth and indiscretion over all else, at least in our ads and entertainment. So which came first: The cultural fetishizing of our twenties, or our brains prioritizing this period in our lives?

Or maybe there's also a biological root the studies aren't able to address. Given that for most of our existence, the human lifespan was around 30 or 40 years of age, isn't it possible that the twenties, when we are at our physical peak and are, at least biologically, expected to have produced children, are actually not the early period in our brains but rather the late period? The twenties are the glory days because for most of human history, they were actually near the end of our lives? We've cheated nature so much with our fiddling, it's hard to tell what's nature or nurture.

In other words, we've so breathlessly fetishized youth in this culture that it seems pretty obvious that we'd hold it up as the most significant, interesting, exciting time in our lives. But is it really? What about the many interesting — not to mention novel — milestones that often can't occur until later in life — looking back on interesting careers, noteworthy inventions, emotional and physical triumphs?

I remember reading a study a while back about how, contrary to what people assumed, older folks didn't spend their days poring over memories of the past, but their minds existed very much in their present relationships and adventures. It was a surprise to researchers at the time, who expected senior citizens to pine for the good old days of their youth. Too bad I can't remember where I read it. I can, however, remember precisely everything I did in my twenties though.

Like it or not, your twenties are here to stay, and will keep revisiting you the rest of your life. So if they are really the Groundhog Day of memories, crank up the tumblrs and enjoy this extra pressure to make this decade really count.